| 摘要 |
PURPOSE:To reliably detect a minute defect, by a method wherein a delay differentiation of a photographing signal is conducted two times, an obtained signal is binary-coded at a different reference level, and a signal generated due to a poor product or a defect is counted. CONSTITUTION:A signal (a) from a camera 1 is amplified to produce a signal (b), and a delay circuit 3 adds a delayed signal (c) to a differential amplifier 4. If a first delay differentiation is conducted through finding of a difference between a signal (c) and a signal (b), a signal wave- form of a good product is inclined to some extent, and in case a contamination or a defect is present, it forms a wave-form which deformed in the middle of inclination. A signal (d) is added to a differential amplifier 6 and a delay circuit 5, a delayed signal (e) is added to a differential amplifier 6, and a signal (f) through finding of a difference between the two signals. Then, through comparison of it with a negative set level (g), in the case of a good product, a binary-coded signal (h) produces 1 pulse, and in the case of a poor product, it produces 2 pulses or more. An output of a comparing circuit 7 is applied to an FF 9 to obtain a signal (i). A theoretical product computation is conducted on the signal (i) and the signal (h) to obtain a pulse output. An output pulse (j) is counted to compare it with a set value A. Meanwhile, a signal (l) binary-coded by means of a positive set level (K) produces 2 pulses in the case of a good product, and 3 pulses or more in the case of a poor product, and an output (q) can be obtained only in the case of 3 pulses or more. |
